Apparatus and method for preheating refractory lined ladles

ABSTRACT

A ladle preheater and method to remove moisture in the lining and set the bond in new refractory liners, to elevate the ladle temperature to that of the molten metal to be poured in order to cut-down on splatter, and to maintain the temperature in the ladle if it is not to be unloaded soon. Automatic drive means are provided for positioning the preheater over the ladle, comprising a refractory lined reflector provided with a gas-fired or oilfired heater supplied by external air circulated by an air blower. The ladle may be supported on its bottom or side for preheating.

United States Patent [191 Leatherby 1 APPARATUS AND METHOD FOR PREHEATING REFRACTORY LINED LADLES [75] Inventor: Vincent C. Leatherby, Glenshaw,

[73] Assignee: Fuel Equipment Co., Inc.,

Pittsburgh, Pa.

[22] Filed: Jan. 23, 1974 [21] Appl. No.: 435,941

[52] US. Cl. 266/1 R; 266/43 [51] Int. Cl. F27D 1/16 [58] Field of Search 214/18 SC; 264/30, 64;

[ Sept. 23, 1975 Primary Examiner-Gerald A. Dost Attorney, Agent, or FirmWilliam J. Ruano [57] ABSTRACT A ladle preheater and method to remove moisture in the lining and set the bond in new refractory liners, to elevate the ladle temperature to that of the molten metal to be poured in order to cut-down on splatter, and to maintain the temperature in the ladle if it is not to be unloaded soon. Automatic drive means are provided for positioning the preheater over the ladle, comprising a refractory lined reflector provided with a gas-fired or oil-fired heater supplied by external air circulated by an air blower. The ladle may be supported on its bottom or side for preheating.

2 Claims, 4 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of3 3,907,260

US Patent Sept. 23,1975 Sheet 2 01 3 3,907,260

US Patent Sept. 23,1975

Sheet 3 0f 3 APPARATUS AND METHOD FOR PREHEATING REFRACTORY LINED LADLES This invention relates to apparatus and methods to automatically and safely preheat refractory lined ladles prior to their acceptance of molten metal.

While I have endeavored, in the past, to preheat the interior of a ladle by a simple torch, this has not been successful since it was impossible to provide even heat in the ladle due to non uniform application of heat and inefficient fuel consumption, resulting in an erratic flame pattern. Also such unstable flame was dangerous to workers, because of the possibility of receiving severe burns from gas explosions,- also from inhaling harmful fumes from the exhaust gases.

An object of the present invention is to overcome the abovenamed disadvantages of uneven heating and dangerous conditions to workmen and, instead, providing uniform heating of refractory lined ladles by a safe and efficient heating apparatus.

A more specific object of my invention is to provide a gas fed, ladle preheater that is provided with an outside source of air supplied by a blower to provide a constant flame, flame safety and having a cover or hood to catch red hot splatter,- also to provide automatic control means for moving both vertically and horizontally the preheater so as to direct radiant heat in the proper direction within the ladle.

Other objects and advantages will become more apparent from a study of the following description taken with the accompanying drawings wherein:

FIG. 1 is an elevational view showing a ladle preheater embodying the present invention and having automatic drive means for moving the preheater both vertically and horizontally to the desired position over a ladle;

FIG. 2 is a modification of the apparatus shown in FIG. 1, illustrated in elevation;

FIG. 3 is an elevational view of a further modification; and,

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3, showing a heating system for preheating ladles while supported on their sides.

Referring more particularly to FIG. 1 of the drawing, the letter L, illustrates, in dash and dot outline, a ladle of any desired height internally lined with the usual refractory liner. Numeral 1 generally denotes a control system for automatically positioning the ladle preheater on top of the ladle L. Such control system includes a vertical cylinder 2 rotatably mounted on pivot bearing 17 and in which a shaft 3 slidably fits. The shaft 3 is integrally secured to a boom 4 which may be raised or lowered, such as to the position shown in dash and dot outline, comprising a vertical travel of about 3 feet or more. By means of a pair of supports 5, 5, a heater reflector 7 lined with a refractory 7a, is supported by boom 4. A gas burner 6 will project a gas flame vertically downwardly along the axis of the reflector and is supplied by a gas supply pipe 21 and an air supply pipe 20 connected to a blower 19.

Horizontal movement of the reflector is provided by a rotating drive and stabilizer generally denoted by numeral l3 and comprising a reversible motor 14 driving a spur gear 15 which, in turn, drives a large gear 16 rigidly secured to two semi-cylindrical elements clamped to shaft 3 so as to move boom 4 horizontally therewith in either direction.

Vertical movement of the reflector is obtained by an elevating drive generally denoted by numeral 9, comprising a reversible motor 10 having a sprocket on its drive shaft and separately mounted sprockets ll, 11, through which is entrained a chain 12 having one end connected to boom 4 and the other end connected to shaft 3. Other means than that described, such as mechanical, pneumatic or manual means, may be used instead to effect'vertical or horizontal movement of the cover. A control panel 18 is provided with the usual switches to energize the driving motor 10 to effect lifting and lowering movements of boom 4 so that cover 7 may control red hot splatter. Splatter refers to red hot particles that look like stars shooting out the top of the ladle in addition to strings of flame. The hot splatter may be hot pieces of refractory conveyed by the pressure from the velocity from the burner or it may be caused by pockets of moisture under the refractory that turns to steam from the heat and breaks off a piece of red hot refractory and throws it out with some great force. Maybe the ladle had been used previously and the splatter could be from some of the impurities left over from the previous load of metal.

The refractory lined cover 7 catches a lot of this splatter but as this cover must be from 6 to 12 inches above the top of the ladle to create a flue area, much of this splatter and hot flue gases escape out of this opening in a 360 arc. The flue gas temperature becomes high as the firing time goes on and the workers do not dare get too close to the ladle. This is why the cover must be located away from the blower and the controls. On the bigger jobs the controls are usually installed remotely.

Because'this cover must be raised and lowered sometimes in order to have the right flue area is part of the reason for the vertical movement of the cover. This vertical movement may be necessary for different size ladles and also if a ladle partially filled with molten metal is placed under the Preheater in order to hold the temperature in the molten metal. With metal already in the ladle the radiant heat from the metal is intense and the cover might have to be raised.

FIG. 2 shows a modification in which the ladle La, denoted by dash and dot outline, is heated by a refractory lined heater head or reflector 26 which is held in slightly inclined position to correspond to the inclination of the mouth of the ladle. A gas burner 27 is provided therein which is fed by a gas supply line 32 and a supply of air which is pressurized by a combustion air blower 30. Valves 31, lead to a vent pipe. The position of the heater head may be varied both vertically and horizontally by control switches mounted on the combustion control panel 20. The heater head may be moved or pivoted either manually or by an electric motor drive.

FIGS. 3 and 4 show a modification for preheating ladles Lb, which are supported on their sides. A blower 39 blows air through blast gate 40 and manifold 41 leading throughbutterfly air valves 43 and unions and brackets 42 to burners 47 which may be fed by a gas manifold supply pipe 44 connected to shut-off valves and pipes 45. The flames of burners 47 are projected through a vertical wall 36 having horizontal openings surrounded by refractory ignition liners 37.

Thus the flames from the burners are projected in the direction of the mouths or openings of the respective ladles Lb.

Another modification is to provide only one vertical refractory heating station with the burner installed and connected by flexible tubing which can be moved from one location to another. This heater station could be stored in an out-of-the-way area and by means of a crane, lift truck or rail cart it could be moved into position for firing into a ladle whenever desired.

The gas-fired preheaters of the present invention are used to raise the temperature on the inside of a refractory lined ladle. The heating is usually necessary for either of the following reasons: (1) to dry the inside lining by removing moisture and setting the bond in the newly installed refractory liner; (2) preheating the inside of the ladle prior to the introduction of the molten metal; (3) or to hold the temperature of the molten metal in the ladle if the ladle is not be be unloaded soon.

The reasons for introducing heat into the ladle for reasons 1 & 3 are obvious. The requirement for No. 2 is to remove any accumulated moisture and to elevate the temperature of the refractory liner near to the temperature of the molten metal that will be poured into it in order to cut down on the splatter, to reduce the shock on the refractory in order to prolong the life of the insulation and to decrease the chill factor in the molten metal.

The ladle preheater of the present invention is designed to burn a fuel cleanly and efficiently inside of the ladle and to heat all of the inside surface as evenly in temperature as possible. The ladles or molds are of a variety of sizes and shapes ranging in capacity from a few pounds to many tons. The shapes of the ladles are such that it is often difficult to maintain a controllable flame and even heat pattern from the top to the bottom by most conventional torches on the market today. This is usually due to the fact that most torches require secondary air inside the ladle for clean burning of the gases.

The preheater of the present invention provides a sufficient amount of primary air from outside of the ladle for complete combustion of the fuel used. This is accomplished by the use of conventional air blowers, compressors or injectors to provide a complete premixing of air/fuel before reaching the burner. If this complete air/fuel mixture is not accurately maintained there is not only an inefficient fuel comsumption but the flame pattern is erratic which causes uneven heating in the ladle, and it can be harmful to the burner equipment. Most important from a safety feature is that a flame is unstable which is dangerous to the workers both from the standpoint of receiving severe burns and also from inhaling of harmful fumes from the exhaust gases.

Because there is a proper air/fuel mixture in the preheater, the flame remains ignited at all times directly on the burner as the burning equipment that I use is not dependent on a hot target wall to stay ignited. The flame safety device must prove that the pilot is operating normally before the main burner can be turned on or ignited. This is a great advantage over many conventional and home made heaters that are presently being used today.

The present preheater may use an automatic electric ignition on a pilot which is provided by an electric relay before the main burner can be started. This feature is a great protection for the workers and from a damaging explosion due to a collection of unburned gases. Most conventional heaters are ignited by a manual lighting torch or by manually igniting a piece of waste material and throwing it on the bottom of the ladle where it is a target to the main burner. If this waste material does not burn enough the main burner does not remain ignited and there is a resulting explosion. Also if an outside draft, an interruption to the fuel supply or an improper burning exists, the flame on the conventional unit can go out and a dangerous explosion can result. As mentioned the preheater has a safety ignition system which is regularly approved by the various safety committees. With the pilot ignited and burning properly and being stable, an electric device will advise through a light system that all is well and the main burner may be started and not before. Everything must be in a safe start condition before the main burner may be started. Also during operation if any device has a malfunction, the controls will make the burner fail safe and not start again until everything is functioning properly. Fuel to the main burner may be supplied automatically by the use of the electronic relay which operates an electric valve or by manually opening an electrically energized valve. Before these valves can be opened separate high or low pressure switches have proved that the fuel supply is correct for proper burning. The electronic flame sensing device continues to operate and if for any reason the flame should become extinguished, the fuel supply will be cut off instantly and it is necessary to start the entire lighting procedure over again. Controls may be located remotely for large jobs for convenience and safety to the workers.

The fuel system has adjustments that can be made to limit the flow and to produce the type of flame pattern that is desirable inside of the ladle. The burner fires from the top down through a refractory lined hood or cover so that the radiating heat is contained inside of the ladle. This refractory cover also minimizes the splatter during heat up periods. The cover can be swung away from the ladle and back again so that the ladle may be moved by an overhead crane. This cover movement including the raising and lowering can be made to move either automatically or manually.

As many automatic devices such as timers, limit switches, signal lights, enunciators, safety switches and fuses can be added to meet the latest safety standards and the customers desires. Whereas only gas-firing has been described, it should be understood that the invention is useful for use of the low BTU gases, such as coke oven gas, natural gas, LP gas or any combination of these gases and also for liquid oil firing or vaporized oil.

While I have illustrated and described several embodiments of my invention, it will be understood that these are by way of illustration only and that various changes and modifications may be contemplated in my invention and within the scope of the following claims.

I claim:

1. Apparatus for uniformly preheating the refractory lining of a stationary, substantially cylindrical ladle and the like prior to pouring therein ofmolten metal, comprising a cover with a refractory lining having an inner concave surface confronting and adapted for covering the mouth portion of said ladle, a burner mounted centrally of said cover and axially of said ladle so as to project a flame from the interior and axially of said lining of said ladle to provide substantially uniform application of radiant heat to said refractory lining of said ladle, a remote source of fuel for said burner, power horizontally relative to the mouth portion of said ladle, and a blower mounted on said boom in an opposite direction from said post relative to said cover for blowing air for combustion through said burner.

2. Apparatus as recited in claim 1 wherein both said ladle and cover have mouth portions which are disposed at an acute angle relative to the central longitudinal axis of said ladle. 

1. Apparatus for uniformly preheating the refractory lining of a stationary, substantially cylindrical ladle and the like prior to pouring therein of molten metal, comprising a cover with a refractory lining having an inner concave surface confronting and adapted for covering the mouth portion of said ladle, a burner mounted centrally of said cover and axially of said ladle so as to project a flame from the interior and axially of said lining of said ladle to provide substantially uniform application of radiant heat to said refractory lining of said ladle, a remote source of fuel for said burner, power driven means for selectively moving said cover either vertically or horizontally relative to said mouth portion of said ladle, a vertical post pivotally supporting a horizontally rotatable boom supporting said cover and said burner, said power driven means including reversible drive means for selectively sliding said boom in either direction vertically of said post or for turning it about the axis of said post to selectively control the position of said cover vertically, to provide a flue spacing, and horizontally relative to the mouth portion of said ladle, and a blower mounted on said boom in an opposite direction from said post relative to said cover for blowing air for combustion through said burner.
 2. Apparatus as recited in claim 1 wherein both said ladle and cover have mouth portions which are disposed at an aCute angle relative to the central longitudinal axis of said ladle. 